On the interstate, you have just passed a franchise of your favorite fast-food chain, and you happen to know that there is another one in 40 miles; but you are very hungry and want to stop earlier. You are pretty sure that there is exactly one restaurant located closer, and the reliability function for the number of miles M until you reach it is:
R(x) = P(X>x) = 1 - x²/1600

(a) On average, how many miles will you have to drive to find this restaurant?
(b) What is the probability that you have driven 30 miles, and still not found the restaurant?